Plastic pipe having an oxygen-impermeable casing

Abstract

A plastic pipe comprising an oxygen-impermeable casing, wherein the casing comprises a barrier layer for oxygen, and an adhesive layer adjacent to the circumferential surface of the pipe and attached to the circumferential surface by an sealed bond, wherein the casing surrounds the circumferential surface on all sides, and wherein the barrier layer is elastic, is substantially impermeable to oxygen and comprises a polyvinyl alcohol, a vinyl alcohol/ethylene copolymer, or polyacrylonitrile. Also disclosed is a process for the production of the pipe and a use of the pipe as a heating pipe.

We claim: 
     
       1. An oxygen-impermeable plastic pipe, comprising: a self-supporting plastic pipe; and   a pre-formed film laminate casing wrapped about said pipe comprising, (a) a heat sealable layer adjacent to the circumferential surface of said pipe and attached to said circumferential surface by a heat sealed bond, and   (b) a substantially oxygen-impermeable, biaxially stretch-oriented, elastic barrier layer adjacent to said sealable layer comprising polyvinyl alcohol or a vinyl alcohol/ethylene copolymer.     
     
     
       2. A plastic pipe as defined in claim 1, further comprising a protective layer comprising a tough, elastic thermoplastic, wherein said protective layer comprises the outer face of said casing. 
     
     
       3. A plastic pipe as defined in claim 1, wherein said casing comprises a hollow cylindrical element slit along the longitudinal axis of said cylindrical element to form cut-edges and comprising overlapping zones of the cut edges, wherein said cylindrical element is formed from a film laminate blank, and wherein said laminate blank formed into said cylindrical element comprises an outer protective polymer layer, said barrier layer and said heat sealable layer adjacent to and attached to said circumferential surface by said heat sealed bond. 
     
     
       4. A plastic pipe as defined in claim 1 wherein said casing comprises a film band wound spirally, in an overlapping manner, over the entire length of said circumferential surface, wherein said film band comprises a laminate, comprising an outer protective polymer layer as the outer face of said band, said protective layer forming the outer face of said casing, said barrier layer adjacent to said protective layer, and said heat sealable layer adjacent to said barrier layer and to the circumferential surface of said pipe. 
     
     
       5. A plastic pipe as defined in claim 1, wherein said barrier layer comprises not more than about 40 mole % ethylene in said vinyl alcohol/ethylene copolymer. 
     
     
       6. A plastic pipe as defined in claim 5, wherein said ethylene is present in an amount not greater than about 20 mole %. 
     
     
       7. A plastic pipe as defined in claim 1, wherein said barrier layer is extensible by at least about 40% at room temperature. 
     
     
       8. A plastic pipe as defined in claim 7, wherein said barrier layer is extensible by at least about 100% at room temperature. 
     
     
       9. A plastic pipe as defined in claim 2, further comprising an adhesive layer between said protective layer and said barrier layer. 
     
     
       10. A plastic pipe as defined in claim 9, wherein said adhesive layer comprises a two-component adhesive comprising a polyurethane. 
     
     
       11. A plastic pipe as defined in claim 10, wherein the thickness of said adhesive layer is negligibly small compared to the thickness of said barrier layer and said protective layer. 
     
     
       12. A plastic pipe as defined in claim 2, further comprising providing a metallic layer vaporization deposited on the inner surface of said protective layer. 
     
     
       13. A plastic pipe as defined in claim 2, wherein said protective layer is transparent. 
     
     
       14. A heating system, comprising at least one iron component and at least one plastic pipe connected to said iron component for circulating a heat transfer agent thereto, wherein said plastic pipe comprises an oxygen-impermeable plastic pipe as claimed in claim 1.